#!/bin/bash
#leao:Wed Aug 21 02:18:06 PM CST 2024
expr 1 + 3
a=`expr 1 + 4`
echo  "a:"$a

#b=$[12+$a]
#b=$[12a+a*2]
b=$[12+a++*2]
c=$((2+a++*2))
echo  "12+a++*2:"$b
echo "a:"$a "c:" $c
i=0
let i++
echo $i
d=[2**3]
echo "[2**3]:" $d